The deterioration of paper, books and newspapers is a well-known and growing concern to librarians and archivists throughout the world. The causes of paper deterioration are numerous and include inherent acidity, photodegradation, oxidation, and even microbiological attack under certain conditions. These factors combined with initial paper quality have severely reduced the permanence of library and archival collections. A host of other phenomenon such as flood, fire, vandalism, etc. certainly add to these problems; however, it is becoming generally accepted that the most insidious problem is the acidity of most book paper produced in the last one hundred years.
The demand for large amounts of printing paper over the last century led to the introduction of pulp fiber produced from wood by chemical or mechanical means. However, paper made from untreated wood pulp is too absorbent to allow sharp image imprint. Therefore, chemicals have to be added to the wood fibers during processing. These additives allow the paper to accept inks and dyes and increase paper opacity. Unfortunately, most of these chemicals are either acidic or are deposited by acidic mechanisms which initiate the slow, but relentless acidic deterioration of paper. Other contributions to the acidification of paper are supplied by man through industrial emissions of sulphur and nitrogen and carbon oxides or by natural processes such as sea salt spray. Even books or paper of neutral and alkaline character are not immune. As neighboring papers of acidic nature degrade, volatile acids are produced which either diffuse through adjoining books or permeate the atmosphere and may ultimately acidify even the "safe or stable" books.
In order to arrest this acidic degradation, paper materials must be deacidified and provided with an alkaline reserve or buffer to retard a return to an acidic state. Currently, there are several processes either in various stages of development or commercialization for deacidifying paper whether bound or unbound. Numbering amoung these are processes using volatile metal alkyls e.g. U.S. Pat. Nos. 3,969,549, and 4,051,276, and volatile amines e.g. U.S. Pat. Nos. 3,472,611, 3,771,958 and 3,703,353. U.S. Pat. No. 3,676,182 issued July 11, 1972 describes the treatment of cellulosic materials with alkali and alkaline earth bicarbonates, carbonates, and hydroxides (Col. 17) in a halogenated hydrocarbon solvent or lower aliphatic hydrocarbon such as n-butane (Col. 7) with an optional plasticizing agent such as ethylene glycol (Col. 9). U.S. Pat. No. 3,676,055 issued July 11, 1972 to Smith describes a nonaqueous deacidification solution for treating cellulosic materials comprising 1000 cc of 7 percent magnesium oxide, (sic magnesium methoxide) in methanol and in addition 20 pounds of dichlorodifluoromethane (Freon 22). Canadian Pat. No. 911,110 issued Oct. 3, 1982 to Smith describes a deacidification solution (p 5) of a 7% magnesium methoxide solution in methanol (10 parts) and a halogenated solvent or solvents (90 parts); and states that a magnesium alkoxide reacts with water in paper to form a mildly alkaline milk of magnesia, being magnesium hydroxide (p 31). Improved results are reported with the use of the halogenated hydrocarbon solvents (p 40).
Unfortunately, all of these processes suffer from one or more of a number of drawbacks that have prevented their wide-spread acceptance. These drawbacks include high cost, toxicity, complexity of treatment, residual odor, deleterious effects on certain types of paper and inks, lack of an alkaline reserve, and the necessity of drying the book or paper to very low moisture contents before treatment.